The Bureau of Economic
Geology and Pemex Exploración y Producción conducted a joint
study of Neogene sequences and depositional systems in the Laguna Madre-Tuxpan
continental shelf between the Veracruz and Burgos Basins. On the basis
of a data set containing six 3-D surveys, >16,000 linear km of 2-D
seismic lines, and >60 wells, this study documents a major system of
sediment bypass on a narrow (10- to 15-km) Miocene shelf, with hundreds
of meters of section dissected by valley-fill and submarine canyon systems
genetically linked to sandy basin-floor-fan systems. Valley-fill and incised-shelf
deposits, inferred from down-cutting, lenticular seismic facies on the
shelf, are narrow (<5 km across), and many are shale filled. In contrast,
canyon systems linked to these valley fills are 5 to 8 km across and contain
a variety of internal architectures. Although some canyons are shale filled,
others are filled with offlapping, progradational delta-front deposits
of highstand origin. The Oligocene Hackberry trend of southeastern Texas
and southwestern Louisiana is an analog for shale-filled submarine canyons
and sandy basin-floor fans in the Laguna Madre-Tuxpan area. The Hackberry
trend is associated with sandy, productive, toe-of-slope fans that were
fed from updip canyon systems notched into the shelf. Isochron maps of
the upper Miocene east of the Tuxpan Platform suggest the presence of
thick, potentially sandy deposits having a similar depositional origin.